Commercially available ceramic matrix composites (CMC's) have many potential applications in high temperature environments. CMC's are limited in their capability for exposure to temperatures near 1,200° C. In addition, CMC's cannot be cooled effectively under high heat flux conditions because of their relatively low thermal conductivity. Accordingly, it is desirable to provide a thermally insulating material for application to a ceramic matrix composite substrate material so that the insulated CMC composite can be used in a high temperature environment such as the hot gas flow path of a gas turbine engine.